320
FXUS61 KCTP 300813
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
413 AM EDT Sun Jun 30 2024

.SYNOPSIS...
A cold front will push through central Pennsylvania later today,
accompanied by scattered showers and thunderstorms this
afternoon into this evening. A large high pressure system will
build into the region tonight and Monday, followed by a dying
cold front pushing in from the Great Lakes and stalling out over
the area by the middle of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Fairly quiet conditions prevailing over much of central PA early
this morning. Mid level clouds have kept areas of fog from
becoming too widespread or dense after the widespread rainfall
Saturday afternoon and evening. Additionally, deep layer
moisture has decreased substantially over the past 24 hours,
with 1 to 1.5" PW across my northern tier this morning where a
plume of 2"+ PW resided yesterday at this time.

Sfc cold front is bisecting OH at this time and crossing Lake
Erie this morning, and much drier air is filtering in behind it
across Michigan where sfc dewpoints drop through the 60s near
Detroit to the mid to upper 40s over northern Lower Michigan.

We can look forward to that air mass for late tonight and
Monday, but have another potential round of convection to
accompany the front as it crosses later today.

Passage upstream surface cold front will bring the chance for
another round of convection Sunday. Locations most likely to see
potential strong/svr t-storms are over the southeastern part of
the CWA due to a fropa coinciding with peak heating of the late
afternoon. CAMs are indicating the best likelihood of strong
storms later today over my eastern counties where moisture and
instability will be greatest and timing of FROPA corresponds
with max afternoon heating. Still, a trend towards lesser
coverage and intensity of deep convection has been noted from
the last few to several CAM runs overall, shifting the greatest
coverage and organization of afternoon storms into eastern PA
and the Catskills. We do expect a sw-ne aligned line of
convection to drop southeastward across central PA from later
this morning through the afternoon, and some storms can contain
strong gusty winds, heavy downpours and small hail. The reward
will be nicely falling dewpoints through the 50s by day`s end
across the northern tier.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Showers and thunderstorms will extend into the early evening
hours over the Lower Susq before the front clears my eastern
counties. It will be breezy and cooler tonight into Monday as a
refreshing air mass similar to last Monday`s drops into the
region. Mins tonight will drop into the upper 40s north and
Allegehnies and through the 50s elsewhere. Highs Monday will
feel even coolish across the north, with some areas struggling
to reach 70, and highs farther south will range through the 70s
to around 80 southeast with breezy conditions persisting into
early Monday evening.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
DCanadian high pressure builds to southern Ontario by Monday
night, bringing a fair and cool night with the high moving
directly overhead. This will result in efficient radiational
cooling and min temps several degrees below normal. Fair and
warmer weather is expected Tuesday into at least the first half
of Wednesday, as upper level ridging builds over the state and
surface high drifts offshore.

All medium range guidance tracks a weakening shortwave well
north of PA late Wednesday into Thursday. The dying cold front
is likely to sag into the state Thursday and stall out in the
vicinity of PA through Friday. Falling heights/surging low level
moisture ahead of the front could support scattered convection
as early as Wednesday afternoon over the northwest half of PA.
However, a better chance of showers/tsra areawide will come
with the arrival of the front Thu into Friday. Early best guess
of late week rainfall based on ensemble plumes ranges from 0.25
to 0.75 inches, with the highest amounts over the N Mtns and
least in the south.

Heat and humidity should peak ahead of the front Wed-Thu.
Ensemble mean 850mb temps surging to near 20C indicate max temps
could reach the low to perhaps mid 90s in the Lower Susq Valley
Thursday, with high humidity pushing heat indices into the mid
and upper 90s. Ensemble plumes suggest slightly cooler daytime
temps late week, due to more clouds/showers. However, high pwats
in the vicinity of the stalling front should result in muggy
nights and above normal min temps the entire second half of next
week.

Models begin to diverge as we head into the weekend. Most
guidance suggests that rain chances stick around through at
least Saturday as another cold front approaches the area.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
Given ample low level moisture beneath a thermal inversion, low
cigs have developed across the northern Alleghenies and Laurel
Highlands. BFD dropped to IFR shortly after 06z, and will likely
remain IFR through sunrise. Farther to the east, restrictions
have generally been limited to the higher elevation airfields
north of MDT. High clouds blowing off of convection to our south
has kept fog development to a minimum, but fog may expand if
higher clouds become thinner towards daybreak.

Much of Sunday will be mostly cloudy with MVFR cigs persisting
across central and western airfields through early afternoon.
A cold front will slide south through the day. Scattered
SHRA/TSRA are expected along and ahead of this boundary mainly
during the afternoon and early evening hours, with MDT and LNS
having the highest chance of seeing vsby restrictions in brief
downpours.

Conditions are expected to improve later Sunday, as the winds
shift to the northwest and much less humid air moves into the
area. The HREF does suggest MVFR cigs are possible at BFD into
Sunday night given upslope flow off Lake Erie.

Monday and Tuesday look dry at this point with VFR conditions,
as high pressure builds into the area. Some valley fog is
possible in the north both mornings.

Outlook...
Wed...PM TSRA moving across from W-E.

Thu...A chance of showers and storms.

&&

.CLIMATE...
At the Altoona Airport, a daily record rainfall of 0.77 inches
was set on Sat, Jun 29. This total breaks the old record of
0.53 inches set back in 1972.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Lambert/DeVoir
NEAR TERM...Lambert/DeVoir
SHORT TERM...DeVoir
LONG TERM...DeVoir/Bauco
AVIATION...Martin/Colbert
CLIMATE...Evans/Steinbugl